LEIGH SALES, PRESENTER: It's been an exceptionally dry and warm winter at both ends of the country and the bushfires that took hold in Sydney yesterday could be an ominous sign of what lies ahead over summer.

Firefighters now have the upper hand on the blazes, but their speed and ferocity were a shock to residents and authorities alike.

As Adam Harvey reports, experts are predicting a brutal fire season in almost every state and territory.

ADAM HARVEY, REPORTER: The fire season has begun. Not with the faint whiff of smoke, but with a red-hot inferno on the edge of Sydney. All it took was one hot, windy day.

BOB ROGERS, NSW RURAL FIRE SERVICE, DEP. COMMISSIONER: Seven weeks since any rain's fallen and we've had an unseasonably warm winter and combined with unseasonably warm conditions on the day. So if you put all those elements together, the fact that when those fires did inevitably start, they just took off very, very quickly.

ALASDAIR HAINSWORTH, BUREAU OF METEOROLOGY: We have had the warmest 12-month period of record across Australia and the warmest winter on record in a number of states.

BOB ROGERS: If there's no meaningful rain in the next short period of time, then it's inevitable we'll get more days like we've had yesterday because it is so dry out there. That long without rain, it is starting to get very, very dry, leaves are crunchy, there's just no moisture left in the fuel.

BOB ROGERS: You'll see there that we have aircraft that fly over these fires, if you can see that screen there, and take images basically of that fire and work out exactly where it is and then we have operators that basically superimpose that over fire maps so that the firefighters on the ground can actually get the benefit of that absolute accuracy of where fires are.

ADAM HARVEY: So you can see the bright yellow spots. That's obviously where the front is burning brightest?

BOB ROGERS: Yes. Yep. So the brighter yellow is where the hottest part of the fire is.

ADAM HARVEY: Without rain, what's happening here will spread across the country. The grim forecast is detailed in this year's National Bushfire Outlook, which says we're facing an unusually bad fire season.

BOB ROGERS: It's inevitable. That's a taste of what's to come for the other states and territories. I think really the entire East Coast is preparing for potentially a difficult season.

ADAM HARVEY: In Western Queensland, where temperatures could hit 40 degrees tomorrow, there hasn't been real rain for two years.

ALASDAIR HAINSWORTH: The grass there is tremendously dry and so above-average fire conditions through Western Queensland and probably into the central parts of Queensland as well.

ADAM HARVEY: Victoria is also likely to have bad fires, but rain this winter means they're not expected until early next year.

EUAN FERGUSON, COUNTY FIRE AUTHORITY OF VICTORIA CHIEF OFFICER: If you live in Victoria, the risk will develop over the next two to three months and we should take heed of the warning from the NSW fires. Now is the time to start planning where your fire breaks are gonna be, start mowing or spraying those fire breaks and fuel breaks. If you live in a household in a rural area, now is the time to start removing those firewood heaps, tidying up around the house.

ADAM HARVEY: It's not only the eastern states that are in trouble. The Weather Bureau's worried about SA and WA.

ALASDAIR HAINSWORTH: Probably particularly concerning for the West Coast of Australia, so the western parts of WA, where rainfalls really have been well below average for this time of year and through winter.

ADAM HARVEY: This unseasonable weather makes burning off more perilous than normal. Yesterday's Blue Mountains fire probably began as a controlled burn lit inside the National Park earlier in the week.

BOB ROGERS: There is the chance that that did reignite. We are examining it. But if we were so risk-averse that if there was any chance of a fire going out, we didn't do a hazard reduction, we wouldn't do many hazard reductions, and then in summer, then you're gonna find more and more intense fires.

ADAM HARVEY: This quick start to the fire season is likely to become a regular event.

ALASDAIR HAINSWORTH: That's what we've seen over the last 12 months, that our extremes have been becoming more extreme. So we've had the hottest summer day on record, we've had the warmest winter day on record in Australia. We're setting these records unfortunately more frequently now than we were before. So, yes, we would say it's a symptom of a warming Australia.